Field of the Invention
The present invention relates to a biaxial hinge suitably used in opening and closing a first casing relative to a second casing of a terminal device such as a notebook PC, a mobile PC and a PDA.
Background of the Invention
Among terminal devices, such as notebook PC, mobile PC and PDA, which comprise a first casing provided with a keyboard portion and a second casing provided with a display portion, uniaxial hinges are sometimes used, wherein the hinges connect the first casing and the second casing, such that both casings can open and/or close in an upward and/or downward direction; in other cases biaxial hinges are employed, wherein each of the hinges comprises two axes, wherein the second casing can further rotate with regard to the first casing, after the former opens 90 to 180 degrees relative to the latter. The present invention relates to the biaxial hinge of these categories.
Conventionally, a biaxial hinge of the above-mentioned structure is known, such as the one disclosed in JP Laid-Open Patent Application No. 2009-063039. The biaxial hinge according to the patent document is characterized in that a shaft attached to a first member (first casing) is connected to a further shaft attached to a second member (second casing) via a joint arm, and that a means for generating friction torque is provided on each shaft, and that a link arm is provided; however, the hinge is not so designed that the first member can open more than 180 degrees relative to the second member, nor that the first casing can open relative to the second casing with regularity.
Recently, requirements for terminal devices such as notebook PC have been diversified, while such terminal devices have diversified their functions accordingly. In order to meet such requirements by allowing such terminal devices to function not only as notebook PC but also as tablet PC, the hinge needs to have a configuration such that it can restrict the opening and closing of one casing, when other casing opens and closes via the hinge between the closed state at 0 degrees and the opened state at 360 degrees, and that the casings can open and close with a prescribed regularity, in that the order of the opening and closing is restricted so as to allow either one of the casings to open and close.
Therefore, the applicant of the present invention has proposed in its previous patent application JP2012-123093 (JP Laid-Open Patent Application No. 2013-249855) a biaxial hinge which is designed such that a first casing can open relative to a second casing up to 180 degrees in each of two upward-downward directions, thus up to 360 degrees in total. This invention itself is certainly useful, but the need arose later to further improve a biaxial hinge such that it enables incremental adjustments in opening and closing angle.
The applicant has proposed a biaxial hinge which meets the above-mentioned additional requirements in its further application (JP Patent Application No. 2013-247542). The configuration of the biaxial hinge is characterized in that a first hinge shaft mounted on the first casing side is coupled in parallel to a second hinge shaft mounted on the second casing side, via a first joint member and a second joint member; that the first hinge shaft and the second hinge shaft are provided such that the former can rotate relative to the latter; a first means for selectively restricting rotation and a second means for selectively restricting rotation are provided between the first hinge shaft and the second hinge shaft, wherein the first means selectively allow the first hinge shaft to rotate and the second means have similar functions on the second hinge shaft; the first and the second means for selectively restricting rotation are constructed such that both means allow the first and the second casings to open and close in a prescribed sequence between the closed state at 0 degree and the opened state at 360 degrees.
In the above-mentioned biaxial hinge, a first means for selectively restricting rotation comprises a first locking member provided between a joint member and a slide guide member, such that the locking member is slidable in an upward and downward direction between a first hinge shaft and a second hinge shaft, wherein comprising a first cam convex portion in an upper portion and a second cam convex portion in a lower portion, wherein the first cam convex portion and the second cam convex portion are independently slidable in an upward and downward direction; a first locking cam member having a first cam concave portion and provided above said locking member, wherein the first hinge shaft passes through and engages with the first locking cam member, and a second locking cam member having a second cam concave portion and provided below the locking member, wherein the second hinge shaft passes through and engages with the second locking cam member. On the other hand, a second means for selectively restricting rotation comprises a third locking cam member attached to the first hinge shaft, wherein a rotation of the third locking cam member is restricted by the first hinge shaft; a fourth locking cam member attached to the second hinge shaft, wherein a rotation of the fourth locking cam member is restricted by the first hinge shaft; a movement stopper rotatably provided between the third locking cam member and the fourth locking cam member, wherein the movement stopper engages with the third locking cam member and the fourth locking cam member, under specific conditions depending on a rotation angle of the movement stopper; a first stopper lever rotatably attached to the first hinge shaft to engage with the movement stopper, wherein the first stopper lever is brought into a pressurized contact with the third locking cam member; and a second stopper lever rotatably attached to the second hinge shaft to engage with the movement stopper, wherein the second stopper lever is brought into a pressurized contact with the fourth locking cam member.
However, a further problem arises, in that there are too many components involved and the structure is too complex, which leads to a high manufacturing costs. A manufacturer of terminal devices such as notebook PC would set very strict demands for reducing the costs of the components of the terminal devices.